Scientists continue to monitor Mount Ruapehu as its volcanic tremors continue.
The temperature of the crater lake on the mountain has dropped over the past week and tremor levels have “generally decreased”, Yannik Behr, GeoNet volcanologist, said.
He wrote that the lake’s temperature fell from a peak of 41°C on May 8 to 30°C on Tuesday.
“The heavy rains of the past week have caused the lake level to rise temporarily and the temperature of the lake to drop. The lake level has now returned to normal levels before the rainfall, while the lake continues to cool. , indicating a general decrease in the amount of heat entering the lake.”
But, tremor levels continued to be “variable”, he added.
READ MORE: Scientists optimistic for Ruapehu ski season as steam plume rises
Behr said the most likely outcome within the next four weeks is “minor eruptive activity” confined to the lake basin, or no eruption.
He said minor eruptions could generate lahars – dangerous volcanic mudflows – in the Whangaehu River.
Behr said sulfur dioxide emissions from relatively shallow magma suggested the volcano “is still at a high level of unrest.”
Thus, the Volcanic Alert Level remains at 2, he said.
“The risk of a prolonged eruptive episode or larger eruption…is higher than two months ago, but within the next four weeks remains very unlikely. Such an eruption would most likely only follow a sequence of smaller eruptions.
“Due to intensified volcanic unrest, GNS Science personnel are conducting more frequent aerial observations and gas measurements when weather conditions permit.”